Silyaxus phillips thompson



(No Model.)

S. P. THOMPSON.

TELEPHONE TRANSMITTER. No. 339,501. Patented Apr. 6,1886.

wi/bmzoaeo wuemtoz I 521 7/ abfio'ml-m o vmsfmmswz iinrrnn STATES PATENTOrricn.

SILVAN'US PHILLIPS THOB'IPSON, OF LONDON, COUNTY OF MIDDLESEX, ENGLAND.

TELEPHONE-TRANSMITTER.

tEPEIQIFICATION form ng part of Letters Patent No. 339,501 dated April6. 1886.

Applicaliou filed August 15, 1885. Serial No. 174,492.

(No model.) Patented in England August 9, i982, No. 3,803.

ters Patent numbered 3,803 of 1882,) of which the following is aspecification.

My invention relates to that class of telephonic transmittcrs in which anormally constant electric current traverses electrodes interposed inthe circuit, and movable with reference to each other, and whichelectrodes are physically acted upon by sonorous airwaves produced bythe voice of a speaker. Devices of this general character wherein aloose contact between two electrodes included in the circuit offers agreater or less resistance to the ilow oi the electric current,according to the degree of intimacy of contact between the electrodes,may be termed current regula tors. The action of the air vibrations orsound-waves upon the current-regulator may be either direct or indirect.In most of the transmitters in practical use-such, for example, as thoseof R-eis, Edison, and Blakethe action is indirect, a stretched membraneor tympanum, or a resilient metallic diaphragm being employed to respondto the vibrations of the voice, and to impart the peculiar vibra torymotion thus taken up from the air-waves to the movable electrode orelectrodes that regulate or control the strength of the electriccurrent. In another form of transmitter, of which the well-known Hughesmicrophone is an example, the mode of action is direct. The sonorousair-waves impinge directly upon a movable electrode, or upon electrodeswhich are loosely in contact with each other,without the intervention ofa tympanum, diaphragm, or other equivalent device.

Oi'thcse two general types of telephonic transmitters thosc inwhich thecurrent-regulator is combined with or actuated by a tympanum ordiaphragm, and those i n which the current-reg ulator is acted upondirectly by the sonorous air-waves-1ny invention relates exclusively tothe latter. I do not make use of a tympanum, diaphragm, or equivalentpartition of any description whatever between the currentregulator andthe air-waves produced by the voice. In my improved transmitter theairwaves produced by the voice of the speaker impinge directly upon themovable electrode or pair of electrodes which constitute thecurrent-regulator. By reason of this direct action I am able to obtain amore accurate correspondence between what is tcchni call ytermed theform of the atmospheric vibrations produced by the voice and the form ofelectrical undulations or waves produced thereby than is practicablewhen a tympanum, diaphragm, or other equivalent partition is used. As aresult of this construction, I am able to obtain a more clear anddistinct articulation in the reccivirig-instrument than has hithertobeen possible. This is especially the case with certain consouantalsounds, which it is found by experience are transmitted imperfectly andwith difficulty by means of apparatus in which the current-regulator isactuated indirectly through a tympauum, diaphragm, or other partition.

It has been found by practical experience that the particular class oftelephonic transmitters to which my improvements relate are liable totwo defects-first, the articulation is less loud than that oftransmitters in which there is a tympanum or diaphragm exposing aconsiderable surface to the air to collect and magnify the vibrations;and, second, if, in on dcr to obviate this difliculty, the speakerplaces his mouth in close proximity to the movable electrodes whichconstitute the current-regulator, the moisture of his breath condensesupon the contact points or surfaces and upon adjacent parts of thecurrent-regulator, impedingits proper action and seriouslyinj uring thearticulation.

To obviate and remedy these two defects is the principal object of myinvention.

In the accompanying drawings several difi ferent forms of telephonetransmitters are shown to which my invention has been applied.

Figure 1 is a side elevation, partly in section, of one form oftransmitter. Fig. 2 illus tratcs a modified form of sound-collector orextended mouth-piece. Figs. 3 and 4 illustrate modified forms oftransmitters.

For the purpose of increasing the loudness of the articulation, which isdesirable when the tympanum or diaphragm is dispensed with, I prefer toemploy mirrors, sound-reflectors, or reverberators formed of glass,metal, wood, or other suitable material, by which the soundwaves aredeflected or thrown aside from their direct path, and are made toconverge directly upon the movable electrode or electrodes of thecurrent-regulator in the same manner that rays of light are reflected ormade to converge upon a given point by means of a polished or reflectingsurface. Such a reflector or reverberator serves to collect thesound-waves proceeding from the speakers mouth, and to so deflect thesewaves that they will converge and impinge directly upon thecurrent-regulator, while at the same time the parts may be soconstructed and arranged that the moisture from the speakers breath isintercepted Actual mirrors of polished metal or silvered glass may beemployed for this purpose, and it may be remarked that these possess theadditional advantage of revealing to the speakers the presence ofmoisture.

The reflector or reverberator is preferably made in the form of anextended mouth-piece. A curved or crooked 1nouth-piecesuch, for example,as I have shown in Figs. 1 and 2, which is so constructed as to retain,intercept, or dissipate the moisture of the breath at the same time thatit deflects the sound-waves directly upon the currentregnlator-servesthese purposes very well.

In Fig. 3 I have shown a flexible speakingtube of considerable length incombination with a eurrentregulator, but without any tympanum,diaphragm, or other partition by which the current-regulator isprotected from the deposition of moisture by the breath. I prefer toform upon the end of such month piece or tube an annular flange, asshown at F in Figs. 1, 2, 3, and 4, as the character of the articulationis thereby improved.

The reflector, reverberator, mouth-piece, or mouth-tube may beconstructed of material which freely absorb moisture, and which willthereby prevent such moisture from being deposited upon the electrodesof the currentregulator. Such absorbent or porous material may, ifdesired, be used for the ease of the instrument. The same result may beattained in still another way,by placing chemical substances capable ofabsorbing moisture within the case of the instrument or mouthtube.

The current-regulator may consist of two electrodes formed of two piecesof metal or of carbon, or of one piece of metal and one of carbon orother conductor of electricity. These electrodes are maintained incontact with each other under slight pressure, produced either bygravity, the resiliency of a light spring, S, or by both these agenciesin conjunction with each other. Such current-regulators are illustratedin Figs. 1, 2, 3, 4, 5, and 6.

In Fig. 4 I have illustrated a form of current-regulator in which thecontact-points O are protected from the moisture of the breath byforming one of the electrodes into a cup, against the concave hollowface of which the other elect-rode bears.

I am aware that a mouth-tube similar to that hereinbeforedescribed,consisting of a flexible tube or of rigid tubes of variousforms, either curved or straight, has been employed in combination withtelephone-transmitters of various kinds.

I claim as my invention- In atelephone-transmitter, the combination,with an electric circuit, of electrodes interposed in said circuit,movable with reference to each other, atube for causing the air-waves toimpinge directly upon one or both of said electrodes, and a flat flangeattached to or formed upon the inner end of said tube and BX- tendingimmediately above the electrodes, substantially as described.

In testimony whereof I have hereunto sub scribed my name this 11th dayof April, A. D. 1885.

SILVANUS PHILLIPS THOMPSON.

Vvitnesses:

BERNARD MnRvYN DRAKE, Janus XVILLIAM BARNARD.

